[Issue 14364] DMD should compile (correctly) SDC test0167.d
https://issues.dlang.org/show_bug.cgi?id=14364 Shammah Chancellor changed: What|Removed |Added Summary|DMD should compile SDC |DMD should compile |test0167.d |(correctly) SDC test0167.d --
[Issue 14364] DMD should compile (correctly) SDC test0167.d
https://issues.dlang.org/show_bug.cgi?id=14364 ag0ae...@gmail.com changed: What|Removed |Added Keywords||wrong-code CC||ag0ae...@gmail.com --
[Issue 14364] DMD should compile (correctly) SDC test0167.d
https://issues.dlang.org/show_bug.cgi?id=14364 ag0ae...@gmail.com changed: What|Removed |Added Status|NEW |RESOLVED Resolution|--- |INVALID --- Comment #1 from ag0ae...@gmail.com --- (In reply to Shammah Chancellor from comment #0) > int ret = 5; > ret += ((ret++ == 5) ? (ret += 3) : (ret -= 11)) + ret; > assert(ret == 23); To arrive at 23 I guess sdc see these values: 5 + 6 + 3 + 9 = 23 ret += ((ret++ == 5) ? (ret += 3) : (ret -= 11)) + ret; That is, sdc takes the value of the lhs before evaluating the rhs. dmd arrives at 27 = 9 + 6 + 3 + 9, meaning it evaluates the rhs before taking the value of the lhs. The spec has something to say about that[1]: > The following binary expressions are evaluated in an implementation-defined > order: > > AssignExpression, function arguments > > It is an error to depend on order of evaluation when it is not specified. For > example, the following are illegal: > > i = i++; So, both sdc and dmd are right and the test case is "illegal". Closing as invalid. [1] http://dlang.org/expression.html --
[Issue 14364] DMD should compile (correctly) SDC test0167.d
https://issues.dlang.org/show_bug.cgi?id=14364 --- Comment #2 from Shammah Chancellor --- So should this not compile? Isn't this at least a DLang Spec problem? --
[Issue 14364] DMD should compile (correctly) SDC test0167.d
https://issues.dlang.org/show_bug.cgi?id=14364 --- Comment #3 from ag0ae...@gmail.com --- (In reply to Shammah Chancellor from comment #2) > So should this not compile? Reading that spec page further: > If the compiler can determine that the result of an expression is illegally > dependent on the order of evaluation, it can issue an error (but is not > required to). The ability to detect these kinds of errors is a quality of > implementation issue. So, compilers are encouraged to reject such code, but they can also accept it and evaluate the sides of the assignment in either order. > Isn't this at least a DLang Spec problem? Feel free to file an enhancement request to specify one true order of evaluation for AssignExpression. --
[Issue 14364] DMD should compile (correctly) SDC test0167.d
https://issues.dlang.org/show_bug.cgi?id=14364 Ketmar Dark changed: What|Removed |Added CC||ket...@ketmar.no-ip.org --- Comment #4 from Ketmar Dark --- actually, compiler must warn about sequence point error. but DMD is for smarts, so it does it's best to carefully hide such errors from programmer. --
[Issue 14364] DMD should compile (correctly) SDC test0167.d
https://issues.dlang.org/show_bug.cgi?id=14364 deadalnix changed: What|Removed |Added Status|RESOLVED|REOPENED CC||deadal...@gmail.com Resolution|INVALID |--- --- Comment #5 from deadalnix --- Reopening. The spec is wrong. It has been discussed many time that should have LTR semantic. --
[Issue 14364] DMD should compile (correctly) SDC test0167.d
https://issues.dlang.org/show_bug.cgi?id=14364 --- Comment #6 from Kenji Hara --- (In reply to deadalnix from comment #5) > Reopening. The spec is wrong. It has been discussed many time that should > have LTR semantic. Can you list the links to the discussions? --
[Issue 14364] DMD should compile (correctly) SDC test0167.d
https://issues.dlang.org/show_bug.cgi?id=14364 --- Comment #7 from deadalnix --- (In reply to Kenji Hara from comment #6) > (In reply to deadalnix from comment #5) > > Reopening. The spec is wrong. It has been discussed many time that should > > have LTR semantic. > > Can you list the links to the discussions? So I reached to Andrei to know the exact details. It turns out this is a point where Andrei and Walter are not in agreement. Andrei advocate for LTR all the way down (as SDC do) and Walter does seems to be inclined to specify it precisely for calls. Anyway, as per spec, a += k is rewritten as a = cast(typeof(a)) (a + k); See http://dlang.org/expression.html, Assignment Operator Expressions for reference. So I think that, even by Walter's standards, as this is not a call, this should be well defined. --
[Issue 14364] DMD should compile (correctly) SDC test0167.d
https://issues.dlang.org/show_bug.cgi?id=14364 --- Comment #8 from deadalnix --- (In reply to Kenji Hara from comment #6) > (In reply to deadalnix from comment #5) > > Reopening. The spec is wrong. It has been discussed many time that should > > have LTR semantic. > > Can you list the links to the discussions? So I reached to Andrei to know the exact details. It turns out this is a point where Andrei and Walter are not in agreement. Andrei advocate for LTR all the way down (as SDC do) and Walter does seems to be inclined to specify it precisely for calls. Anyway, as per spec, a += k is rewritten as a = cast(typeof(a)) (a + k); See http://dlang.org/expression.html, Assignment Operator Expressions for reference. So I think that, even by Walter's standards, as this is not a call, this should be well defined. I opened a thread on the newgroup: http://forum.dlang.org/thread/dqkqvnkgxkxncyvyi...@forum.dlang.org#post-dqkqvnkgxkxncyvyitid:40forum.dlang.org --
[Issue 14364] DMD should compile (correctly) SDC test0167.d
https://issues.dlang.org/show_bug.cgi?id=14364 Ketmar Dark changed: What|Removed |Added CC|ket...@ketmar.no-ip.org | --
[Issue 14364] DMD should compile (correctly) SDC test0167.d
https://issues.dlang.org/show_bug.cgi?id=14364 --- Comment #9 from deadalnix --- Update : It turns out DMD has the intended behavior. However, the spec need to be fixed. a += b do not decay as a = cast(typeof(a)) (a + b) but as : ((ref i, auto ref j) => i = cast(typeof(i)) (i + j))(a, b); --
[Issue 14364] DMD should compile (correctly) SDC test0167.d
https://issues.dlang.org/show_bug.cgi?id=14364 deadalnix changed: What|Removed |Added Component|DMD |websites --
